The inventor in Delft is the ordinary keeper of the main chamber at the city hall. He is an illiterate, but ingenious man. He allows one to view through his glasses, but he does not want to give or sell them. To the Duke of York [the later King James II of England] even he has refused it; as to the Frisian Stadtholder [Hendrik Casimir II of Nassau-Dietz] and others.

There are other kinds of microscopes, but those of Delft seem to be the most revealing. Except the usual [microscopes], he has exceptional inventions, which magnify extraordinarily, but which he never shows. He has many viewers, who sometimes offend him, which makes him [a] difficult [man].